1. Field of Invention
The invention relates to an image forming apparatus that includes a recording medium feeding device that feeds a recording medium, one by one, from stacked recording mediums, and to recording medium feeding apparatuses that can be stacked one upon the other under the image forming apparatus.
2. Description of Related Art
A conventionally-known image forming apparatus separates a recording medium, such as a recording sheet, one by one, from stacked recording mediums accommodated in a cassette using a separator, such as a sheet feed roller, and forms an image on the separated recording medium in a main body of the image forming apparatus. Each recording medium feeding apparatus is structured so that the recording medium feeding apparatuses can be stacked one upon the other. Therefore, for example, a plurality of the recording medium feeding apparatuses are provided according to the size of the recording mediums (such as for B5-size, A4-size, or B4-size sheets). By stacking the recording medium feeding apparatuses one upon the other, a desired size recording medium can be fed from the recording medium feeding apparatus accommodating the desired size recording mediums therein.
In this case, the plurality of the recording medium feeding apparatuses are stacked so that the desired size recording medium is fed, to form an image in the main body of the image forming apparatus, without changing the cassette. In the image forming apparatus, the desired number of the recording medium feeding apparatuses can be stacked one upon the other. Thus, the image forming apparatus does not become oversize.
However, when the plurality of the recording medium feeding apparatuses are stacked one upon the other, a feeding path of the recording medium becomes longer for each successively lower recording medium feeding apparatus. This easily causes a deviation of the recording medium, that is a skew of the recording medium. Generally, upstream of an image forming unit, for forming an image on the recording medium, a deviation adjusting means, such as a resist roller, is provided. The deviation adjusting means temporarily stops a leading edge of the recording medium to adjust the deviation of the recording medium. However, if the feeding path of the recording medium becomes long, the deviation adjusting means may not satisfactorily adjust the deviation of the recording medium.
The invention provides a recording medium feeding apparatus and an image forming apparatus that can effectively limit the deviation of a recording medium.
According to one aspect of the invention, an image forming apparatus includes a plurality of recording medium feeding apparatuses that can be stacked one upon the other, an image forming apparatus body, first deviation adjusting means that is provided upstream from an image forming unit that forms the image in the image forming apparatus body, and second deviation adjusting means that is provided downstream from the separator in each of the recording medium feeding apparatuses. Each of the recording medium feeding apparatuses accommodates a cassette that holds a stack of recording mediums, has a separator for separating the recording mediums, one by one, from the stack, and feeds the separated recording medium. The image forming apparatus body can be stacked on top of the recording medium feeding apparatuses and forms an image on the recording medium fed from one of the recording medium feeding apparatuses. The first and second deviation adjusting means temporarily stop the recording medium to adjust its deviation while contacting a leading edge of the recording medium. The second deviation adjusting means also functions as conveying means for conveying the recording medium fed from one of the lower recording medium feeding apparatuses toward the image forming apparatus body.